1. Field of the Invention
This invention relates generally to an apparatus for moving cylindrical objects through the ground, and more particularly to hydraulically operated equipment for pushing pipe through existing underground pipe.
2. Brief Description of the Prior Art
The prior art includes several patented devices for pushing pipe in underground conduit. Some of the more pertinent devices are Reed U.S. Pat. No. 3,774,286; Schosek U.S. Pat. No. 4,274,758; Akesaka U.S. Pat. No. 4,662,606; and Shy U.S. Pat. No. 4,842,248.
Reed U.S. Pat. No. 3,774,286 discloses a machine including a frame adapted to be prepositioned in an excavation adjacent the open end of a long, straight run of an underground pipeline. The frame supports a power-actuated, reciprocable pusher head disposed--when the frame is in place in the excavation--in axial alignment with said open end of such run, and operative to successively, forcefully thrust liner pipe sections, in end-coupled relation, thereinto.
Schosek U.S. Pat. No. 4,274,758 discloses a pair of elongated abutment members provided in a parallel arrangement outwardly of respective sides of an underground pipe installer device. A link arrangement connects the abutment members to the respective sides in a manner whereby the spacing between the members may be forcibly expanded by utilizing the drive forces of the pipe installer by interconnecting an underground hole-forming rod, conventionally engaged in the installer to the link arrangement during a forward drive operation thereof.
Akesaka U.S. Pat. No. 4,662,606 discloses a pipe-propelling device comprising two sets of jack assemblies spaced from each other and arranged in the direction of propelling the pipe in a vertical shaft having a reacting shaft wall so that the small diameter pipe, such as water supply and drainage pipes, gas pipes and cable-laying pipes, can be propelled from the interior to the exterior of the vertical shaft by the extension of two sets of the jack assemblies.
Shy U.S. Pat. No. 4,842,248 teaches an hydraulic apparatus for pushing and pulling rod or pipe underground. The apparatus includes a frame for mounting an hydraulic cylinder and a carriage.
The present invention is distinguished over the prior art in general, and these patents in particular, by a hydraulic apparatus for pushing pipe into an underground pipe which comprises a hydraulic cylinder mounted on two longitudinally spaced sets of three radially extending, equally spaced legs. The legs have adjustable locking devices for locking the hydraulic cylinder in place as required inside the one part of an underground pipe. The hydraulic cylinder also has a lock plate of a length longer than the diameter of the underground pipe which acts to anchor the hydraulic cylinder in place when the hydraulic cylinder is activated. The apparatus has a head or push plate attached to a ram or piston extending from the hydraulic cylinder and a hydraulic control valve controlling actuation of the cylinder. With the two sets of legs attached, the hydraulic cylinder is placed inside one part of an existing underground pipe which is near the part in need of repair and the legs adjusted to secure the cylinder tightly in place. The lock plate presses against the end of the underground pipe in which the cylinder is secured. The push plate contacts the end of the section of pipe which is to be pushed into the existing underground pipe in need of repair. The hydraulic cylinder is activated by the control valve and the ram and push plate push the repair pipe into the existing underground pipe.